Outdoor Exposure
==== Cancer Medium Frequency ====
The outdoor/UV exposure variables (from e5
), allow us to adjust for differing sun exposure from:
* weekdays and weekends,
* summer and winter,
* sunscreen strength and application frequency, and
* state-level uv exposure.
To accommodate variation in time, the above questions were asked twice: once for the past year and and a second time for 10 years ago. We calculate relative UV exposure using the following formula:
$$\text{OUTDOOR_AVG} =
\sum_{yr}^{\{1, 10\}}
\sum_{seas}^{\{sumr, wint\}}
\text{UVstate}_{seas} \times
\text{RFspf}^{yr} \big(
5 \, \text{EXwkday}_{seas}^{yr} +
2 \, \text{EXwkend}_{seas}^{yr}\big) \big/ 7
$$
where (questionnaire variables are in parenthesis: where $i \in\{1,2\}$)
* $\text{RFspf}^{yr}$ is a unitless UV Reduction Factor based on the subject's sunscreen type (SPFi) and their usage pattern (SUNSCRNi),
* $\text{UVstate}_{seas}$ is the per-season average daily peak UV-index for a select city from each state (Seasons: summer (April - Sept) and winter) 1, and
* WeekdayEX (WRMWKDi and COLWKDi) and WeekendEX (WRMWKEi and COLWKEi) are the number of hours a subject spends in the sun.
Below is a comparison of the UV-adjusted OUTDOOR_AVG and the average outdoor_hours_per_day.
* Subjects who consistently wear high-SPF sunscreen lie near the bottom of the chart.
* The continuum between zero and maximum exposure is due to subjects living at differing latitudes.
* The five ridges corresponding to distinct slopes, likely represent geographic locations (states) with high population.
''S:\SHARED\RESEARCH\Projects\Cancer Medium Frequency\Setup''
VitD Bone Density - Fracture Risk project
Subjects are categorized by the average sun exposure per day.
| out_cat4 | Outdoor exposure |
|---|---|
| 0 | The subject spends less than an hour outside each day |
| 1 | The subject averages between 1 and 3.5 hours outside |
| 2 | The subject averages over 3.5 hours outside each day |
''S:SHARED\RESEARCH\Projects\VitD Bone Density- Fracture Risk\Setup Code - Release Recipes''